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Nodal benches 1–4 have long been used to characterize optical system performance. The chief feature of a nodal bench is the nodal bearing which rotates the lens over its nodal point for off-axis evaluation. When this is done, there is no displacement of the image in the paraxial image plane. Any image displacement noted as the lens is rotated over its rear nodal point is a direct measurement of distortion. Parameters such as* Equivalent, Back, and Flange Focal Lengths,* Blur Spot Size,* Field Curvature,* Distortion,* Lateral Color,* Aerial Image Resolution, and* Spherical Aberration can be directly measured on a nodal bench. Visual examination of an image is many times the most effective way to judge optical quality and to diagnose lens defects.